Hey folks, acquired this car a few months back with a blown motor (piston was in pieces in the oil pan), got a new one off of CL with about 240,000. After about 500 miles, its got a pretty good "down low" knock at startup for a minute or so. Sounds to me like a rod bearing?

Question is, could I remove the upper oil pan in the car? Has it been done, or does the motor need to come out again?

If it is like a 5 cyl, I believe you can replace the front 2 rod bearings without removing the upper oil pan or the engine. However, if a rod bearing is bad, chances are that the rod itself is out of round. It may not do any good to replace bearings, as the crank journal may be bad as well. You may just have an injector nailing problem. The sound of injector nailing and rod knock is identical. If the engine idles/runs smooth, then chances are it's a rod knock. If the engine idles/runs rough, it could be injector nailing. If the oil smells burnt, it is definitely a rod knock.